I cannot remember where I saw one, but I recently saw a guitar with angled frets somewhere on the internet. It looked interesting, so I did a little research. The correct name for such a guitar is a multi-scale or fanned-fret guitar. The big benefits of a multi-scale guitar seem to be expanded tonal range, improved string tension, better intonation for lower (downtuned) tunings, and improved playing ergonomics. They seem to be made mostly as 7- or 8-string guitars. Surprisingly, at least to me, a lot of them are headless guitars.
Has anyone tried a multi-scale or fanned-fret guitar? Does anyone own one? Share your thoughts, reviews, and experiences in the comments below.